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途经环境敏感地段的埋地油气管道周围铺设膨润土垫,可以减小管道泄漏对周边环境造成污染的风险,但也可能对管道阴极保护电流散流产生屏蔽作用。为了研究膨润土垫对管道阴极保护电流的屏蔽程度,建立了异性土壤结构下管道电位计算模型。基于边界元法,对铺设膨润土垫前后不同阴极保护电流下的管道电位分布、管道自然电位一定时阴极保护范围随土壤电阻率的变化关系进行了计算。选取工程中已铺设膨润土垫的1 500 m管段进行建模计算和现场测试,计算和测量在距管道首端200 m处的管道注流点电位变化,计算结果与测量结果具有较高的吻合度,从而验证了算法的准确性。
Laying bentonite mats around buried oil and gas pipelines passing through environmentally-sensitive areas can reduce the risk of pipeline leakage polluting the surrounding environment, but may also shield the cathode cathodic protection current from dispersing. In order to study the shielding effect of bentonite mats on cathodic protection current of pipeline, a calculation model of pipeline potential under the heterogenous soil structure was established. Based on the boundary element method, the pipeline potential distribution under different cathodic protection current before and after the laying of bentonite mat and the relationship between the cathodic protection range and the soil resistivity when the natural potential of the pipeline is constant are calculated. The 1 500 m section with bentonite mat laid in the project was selected for modeling calculation and field test to calculate and measure the change of electric potential at the pipeline injection point 200 m away from the head of the pipeline and the calculated results were in good agreement with the measured results , Which verifies the accuracy of the algorithm.